<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title></title>
    <script type="text/javascript">
      window.onload = function () {
        //分别为两个按钮绑定单击响应函数
        var btn01 = document.getElementById('btn01');
        var btn02 = document.getElementById('btn02');

        btn01.onclick = function () {
          alert(1);
        };

        btn02.onclick = function () {
          alert(2);
        };

        //设置btn01对鼠标按下相关的事件进行捕获
        //当调用一个元素的setCapture()方法以后，这个元素将会把下一次所有的鼠标按下相关的事件捕获到自身上
        btn01.setCapture();
      };
    </script>
  </head>
  <body>
    <button id="btn01">按钮01</button>
    <button id="btn02">按钮02</button>
  </body>
</html>
